The invention concerns a textile machine, especially an open-end spinning machine with a plurality of production units respectively having a device for determination of the transverse dimensions of running yarn, connected via electronic switching circuits and intermediate storage to a common data processing facility.
In yarn-producing textile machines, e.g. in open-end spinning machines, there are yarn defects that lead not only to yarn breaks but also to fluctuations of yarn thickness or other irregularities. These yarn flaws can pronouncedly affect further processing and in some circumstances the surface texture from this yarn will end in production of goods that have to be rejected. This is especially true of slight fluctuations in thickness and other irregularities that occur periodically at regular intervals, where the surface texture produced from this yarn has a moire appearance. In ravelling out of unknitting yarns, there can be substantial extra cost involved, even if only a single spool has a defective yarn.
To manage the difficulties indicated above, and to prevent production of defective yarn by individual production units of a spinning machine, even temporarily, it is known from German AS 2,409,882 that with each spinning station there can be associated a device to determine the transverse dimension of the running yarn, the measurements being worked up by a data processing facility. If something unusual occurs, the indicator instruments associated with the spinning station in question will be actuated (signal light, alarm bell, relay switch). This arrangement requires a considerable outlay for electronic and mechanical components to be installed at each spinning assembly, so that it seems questionable, that such outlay would be acceptable in proportion to their use.
In a melt spinning machine, it is also known, from Swiss Pat. No. 551,923, that yarn defects can be determined by electronic sensors and that signals dependent therefrom can be taken to a data processing instrument common to all production units, this processing instrument being connected periodically with the individual production units. This data producing instrument then works up or processes the data delivered to it from the respective units with which it is connected at the moment. In order not entirely to neglect yarn deflects that may occur in the meantime, there are intermediate storage devices associated with each production unit, which are switchable in two binary states. The coarse yarn flaws which may be stored there are than taken in the next sensing period to the date processing instrument instead of the signal taken directly from the production unit in question. Here also there is still a considerable outlay both for electronic and mechanical components that have to be available to evaluate the measurement signals taken at the individual production units, which may be taken from yarn defects. Moreover, only coarse yarn flaws are stored in the intermediate periods.
It is also known (British Pat. No. 1,375,254) that a servicing instrument may be caused to travel past a spinning machine with a plurality of production units winding yarn to spools, said instrument being equipped with detectors that can detect malfunctioning of the individual stations. These detectors are connected with data processing facility that can travel with the servicing instrument, further to work up the malfunctions determined from the outside of the individual production units, and to allow suitable countermeasures. This servicing instrument is not capable however of automatically monitoring the quality of the running yarn and initiating and executing actions, from the date on yarn quality.
The invention is intended to make it possible, in a textile machine of the specified type, to monitor the running yarn without having an excessive outlay for electronic and mechanical components. The invention consists therein that the intermediate storage devices are stationarily disposed in the region of the individual production units, and in that for several or for all production units that is a mobile servicing device or instrument that can be moved along the textile machine, said servicing instrument including a process computer and means to connect the process computer with the intermediate storage of a production unit, as well as at least one function element that is controlled by the process computer and that can be presented to the production unit concerned, for execution of a servicing operation.
By this arrangement it is possible to limit to a minimum the electronic devices needed on each production unit, whereas no extra mechanical devices need be present on the production units in question. By storage of the measurement data, only a relatively short residence time is required for the servicing instrument at the production unit to be serviced, without an unwarranted limitation of the measurement period. It is thereby possible to associate the servicing instrument with the common process computer of a very large number of production units.
The servicing instrument, by means of its function elements, can directly engage in the individual production units and effect a servicing operation without causing a halt.
In a simple embodiment of the invention, it is provided that the servicing instrument will include a function element for characterizing a malfunctioning production unit. In this way it will be easy for the operating personnel to find such malfunctioning units and possibly eliminate the cause of the malfunction.
In preferred embodiments, it is also provided that the servicing instrument will have a function element for interruption of the work process of a malfunctioning production unit. This interruption is important if the yarn flaws that have been detected are so serious that further processing of the produced yarn would not be worthwhile. It may also be provided, according to certain embodiments, that the servicing instrument will have a function element which can be presented to a switch that will prevent automatic switching on again of a malfunctioning production unit. By this arrangement, it is ensured that the production, once stopped by the servicing instrument because of serious yarn flaws, will not be put back into operation without removal of the cause of the defects. To monitor the quality of the individual production units and their susceptibility to disturbance, it may further be provided that the servicing instrument will have a device controlled by the process computer, to issue a control sheet showing the measurements from the tested units.
Since the servicing instrument only passes by the individual production units periodically, there is the risk that in the meantime a yarn will be produced and spun on a spool that has unacceptable defects. In order not to have the whole spool become a reject, in a further embodiment of the invention it is provided that the servicing instrument will have a device for winding off and separating a yarn length determined by the process computer, said device being controlled by the process computer and being capable of being presented to a winding spool of the production unit being tested. It is then determined by the process computer that enough will be wound off to remove the flawed places from the spool. In some situations this winding off will have to go so far that the whole length of yarn will be removed that had been spooled between two monitoring periods.
In a further embodiment of the invention it is provided that the process computer with its interrogating and control devices and with the function elements that it controls will be combined with a traveling servicing device that can execute cleaning and/or yarn piecing and/or spool exchange on the production units. Such servicing devices in a number of cases are already available, so that the outlay for the servicing instrument that will accept the process computer can be diminished. It is especially advantageous to couple the servicing instrument containing the process computer with a traveling spool exchange device, because it is then ensured that no spool exchange will occur without a check of the last yarn that was wound, for freedom from defects.
In a further embodiment of the invention it is provided that each production unit will have a trigger circuit synchronized with the winding spool drive, that controls a periodic storage of measurements in the intermediate storage. This arrangement is advantageous because then the storage capacity of the intermediate storage can be kept to a reasonable size. The periodic storage is to be turned with the desired monitoring function.
In a further embodiment of the invention the device for determining the cross section dimension of the running yarn is connected via two switching circuits with the appurtenant intermediate storage, whereof one is made as an evaluating stage and the other as a conversion stage. Such an arrangement is sufficient for the wanted testing purposes. In order to have detection of periodically occurring yarn defects that lead to undesired moire effects, in an advantageous embodiment of the invention there is an evluation stage provided which produces signals that correspond to the temporal succession of variations of yarn cross section. In this case, it is not absolute values of cross section variations that are involved, but only their position in the produced yarn. Even relatively slight variations in cross section that normally could be ignored sometimes can make the yarn unusable, if they occur periodically.
In order to determine yarn uniformity, in a further embodiment of the invention there is a rectifier stage used as evaluation stage, and an averaging stage connected in series therewith. In this case the uniformity of the yarn is the testing criterion.
If the number of thick and thin places is to be checked as testing criterion, in a further embodiment of the invention, a series circuit comprising comparator and pulse counters is provided as the evaluating stage.
If excessive fluctuations of thickness of the yarn are used for the testing criterion, according to a further embodiment of the invention, it is provided that the evaluation stage will include a comparator and a holding stage, which is connected via a switch controlled by the comparator with the device for determination of cross section dimension of the running yarn and connected to the converter stage.